One challenge will be proving the Labour candidate’s pro-nuclear credentials, with Sellafield nuclear plant a key local employer.
Photograph: Gary Calton for the Observer

Cumbria’s woman of the year, a local NHS campaigner and Labour’s former candidate in Penrith have made the all-female shortlist for the marginal Copeland byelection.

Rachel Holliday, Gillian Troughton and Barbara Cannon are the candidates shortlisted by a panel from Labour’s national executive committee, in a seat where the Conservatives need just 2,500 extra votes to win.

If Theresa May’s party took the seat, where a majority voted leave in the 2016 EU referendum, it would be the first byelection victory for a sitting government since the Mitcham and Morden constituency was won by the Conservatives in 1982, when the sitting Labour MP resigned to join the SDP.

The Copeland byelection was triggered by the resignation of Jamie Reed, a prominent critic of the Labour leader, Jeremy Corbyn, who quit before Christmas to take a communications role with Sellafield, stating a desire to be closer to his family.

The campaign will be masterminded by Labour MP Andrew Gwynne, who ran the campaign that successfully saw off a strong challenge from Ukip in the Oldham and West Royton byelection last year.

One challenge will be establishing the Labour candidate’s pro-nuclear credentials, with Sellafield nuclear plant a key local employer. Conservative activists have already begun distributing leaflets with anti-nuclear quotes by Corbyn.

The selection panel of four included three NEC members with close ties to the leadership, Christine Shawcroft, Labour MP Jon Trickett and Unite’s Jennie Formby.

Corbyn’s office is understood to prefer Holliday, a local Unite activist named Cumbria’s woman of the year in 2015.

Holliday founded Time to Change in west Cumbria, a social enterprise that tackles homelessness, and Calderwood House hostel for the homeless. She also set up a local homeless football team, telling the local press she had a passion for the issue having been homeless herself during her teenage years.

Former Labour MP Thomas Docherty had also officially put his name forward to stand for the party but was not shortlisted. Born in Cumbria, Docherty was MP for Dunfermline and West Fife until he lost his seat in 2015.

Others on the NEC are thought to prefer Troughton, a trained orthopaedic surgeon and local councillor, because of the intention to focus the campaign on the NHS. Cannon, a councillor in Allerdale, has election experience, having stood against Conservative MP and international development minister Rory Stewart in Penrith and the Border in 2010.

Shortlisted candidates will attend a hustings in the constituency next week where the final candidate will be chosen.

On Thursday, the Liberal Democrats announced West Cumbria councillor Rebecca Hanson would be their candidate in the seat, where they received just 3.5% of the vote in 2015.